Method of preparing solutions of gases.



No. 889,132. PATENTED MAY 26, 1908.

H. HOWARD. I METHOD OF PREPARING SOLUTIONS 0 P GASES.

APPLICATION FILED NOV. 5, 1906.

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HENRY HOWARD, l) l N O Rlll WUB lfliN MA SSA GHU SE'lTS.

. METHOD OF PREPARING SOLUTIONS OF GASES.

Specification off Letters Patent.

Patented May 26, 1908.

Application filed November 5, 1906. I Serial No. 342,132.

To all whom it may concern:

Bait known thatl, HENRY llownnn, a citizen of the United States,residing at North \Noburn, in the county of Middlesex and Stateof-Massachusetts, have invented certain new and useful Improvements inMethods of Preparing Solutions ofGases, of which the following is aspecification.

,This invention is a method of preparing solutions ofgases of anydesired concentration y The invention will be described asapplied to thepreparation of suliite liquors containing free sulfur dioxid, but is notrestricted thereto.

In the use of suliite solutions for the production of cellulose, it isessential for the most eifective and economical working that thesolution should contain a certain proportion of uncombined sulfurdioxid, and that this proportion should be within the control of theoperator. Whensuch liquors produced by subjecting a solution containinglime or other base to contact with sulfur dioxid produced by burningsulfur or pyrites' in air, and more particularly in the latter case byreason of the greater dilution of the sulfur dioxid, it oftenoccuirsthat tho'percentage of free sulfur dioxid is less than is desirable ornecessary. According to my invention such percentage is increased to anydesired extent, up to the amount corresponding to the saturation pointof a solution of given temperature under an atmosphere of pure sulfurdioxid at a given pressure, I accomplish this result by bringing thediluted sulfur dioxid produced by the combustion of sulfur or of pyritesinto contact with a sol-,

vent liquor, such for instance as water, and

absorbing it therein; I then expel the absorbed gas from such liquor ora portion thereof, and after separating part or all of the moisture fromthe gas, if this should be deemed desirable, 1 cause the gas to beabsorbed, to the desired extent, in the-suliite liqunr or otherabsorbing medium. Preferably, 1 prepare a solution of sulfur dioxid orsulfurous acid by absorbing burner gases in water under atmos her1c orhigher pressure,

and. subsequently expel the gas from said solution or any requiredportion thereof and absorb it in the sullite or other liquor, therebysup plying such quantity of gas to the liquor as may be required, orincreasing the gas content of the same to any deslred extent. The

' liquid from which the gas has been expelled is then brought intocontact with the burner gases for restoring its content of sulfurdioxid. The method is readily made continuous, and any desired sulfurdioxid content is secured by properly proportioning the quantity ofsolvent from which. the gas is expelled to that of the absorbing mediumin which the expelled gas is absorbed. Preferably also, I effect aninterchange of heat between the expelled gas and the inllowing solution,and between the heated liquor and inllowing solution, wherebyconsiderable economy is effected.

For a full understanding of my invention reference is made to theaccompanying drawing wherein the figure is an elevation, partly insection, of one form of apparatus for carrying my method into effect.

1 is a storage tank for suliite liquors prepared from burner gases inthe usual manner. 2, 3 are saturation tanks wherein the sulfur dioxidcontent of this liquor may be increased, and L is a storage tank for theresulting suliite solution. Solution ilows from tank 1 through pipe 5having a cock 6 to the saturater 2, overflows therefrom through pipe 7to the saturater 3 and passes thence by pipe 8 to the storage tank 4.

1 1s a stora e tank for water or other solvent contaunng sulfur dioxid,the solution having preferably been prepared by the use of burner a'sesas above mentioned: from b tlns tank solution is )ernutted to flow throuh a pipe -10.prov 1ded with a cock 11 to a boller or sulfur dloxldgenerator 9, traversing 1n its passage two heaters or heat-interchangers12 and 13 each of which is shown as com'pnsing'a coil'within a closedtank, the solution from tank 1 passing around .the coil in heater 12 andthrough the coil in heater 13: From heater 13 the solution'passes bypipe 14 to the generator 9, This generator-may be pf any'suitableconstruction; as shown it comprises a relatively shallow closed tanksubtivided into several compartments 'or partitions 15,.16 so arran edas ,to afford a restricted communication etween adjacent compartments,liquid being introduced at ator 9 through pipe 22,

13 thence one end of the tank through pipe 14, traversing the severalcompartments in succession and .escapin at the opposite end through pipe17. Live steam is blown into the generator through pipe 18'having inletsto the several com artments, and serves to expel the sulfur ioxid fromthe solution therein. The ex elled as, together with the steam, is conucted t rough pipes 19 to the coil in heater 12, imparting a portion ofits heat to the solution from tank 1; it may then be further cooled bymeans of water or other cooling medium in a condenser 20, and passesthence to a separator or trap 21 of an usual construction. The separatedliqui consisting of water saturated with sulfur dioxid, flows from thetrap 21 to the generpreferably traversing the heater 13 as shown.The-substantially pure sulfur dioxid is conducted from the trap 21 bypipe 23 to the saturater 3 wherein it is whol y or in part absorbed bythe liquor from tank 1, any unabsorbed portion passing by pipe 24 tosaturater' 2 thence by pipe 25 to be added to the burner gases andutilized in the reparation of further quantities of sulfite solhtion orof the aqueous or other solution from which the gas is to be expelled.The heated solution from which sulfur dioxid has been expelled in thegenerator 9 overflows therefrom through pipe 17 into heater it may bepermitted to flow by pipe 26 to a cooler 27 in which it' is fully cooledby water, passing then through pipe 28 to the usual absorbing systemwherein it is brought intocontact with the burner gases and pre ared forfurther use.

It wi be observed that the volume and sulfur-dioxid content of theprepared solution passing to'the storage tank 4 is absolutely controlledby manipulation of cocks 6 and 11, the concentration'of this solution awith respect to sulfur dioxid being increased or diminished by ermittinga smaller quantity 0 the solution rom tank 1 to pass to the generator 9.In practice cocks 6 and 11 are so manipulated as to insure at all timesthe preparation of solution corresfponding in volume and in the percentage 0 absorbed gas to the requirements of the digesters. I f

In my Patent 836,500, issued Nov. 20, 1906, I have described and claimeda method of preparing solutions of gases consisting in expelling the gasfrom one' ortion of a partia ly saturated liquid, an absorbing it inanother portion of the same liquid, the portion of the liquid from whichthe gas has been expelled bein -thereafter subjected to contact with aditional' saturate it.. The'specific invention herein described andclaimed differs from the abtive in that the gas expelled from a liquid,which reater or gas to again partially solvent by contact with the gasin diluted form, then expelling the gas from the result ing solution andabsorbing the relatively concentrated gas in an absorbing medium otherthan said solution, whereby, a solution of relatively high concentrationis obtained, substantially as described. r

2. The method of preparing sulfite solutions, which consists indissolving sulfur dioxid in Water by contact with the gas in dilutedform, then expelling the gas from the water'and absorbing the relativelyconcentrated gas in. a sulfite solution, substantially as described.

3. The method of pre arin'g solutions of gases, which consists inissolving 'a gas in a solvent by contact with the gas in diluted form,then expelling the gas from the resulting solution and absorbing therelatively concentrated gas in an absorbing medium other than saidsolution, whereby a solution of relatively high concentration isobtained,

and subjecting the liquid from which the gas has been expelled tocontact with additional gas to restore .its content thereof,substantially as described.

4. The method of pre aring solutions of gases, which consists 111ssolving a gas in a solvent by contact with the gas in diluted form,then expelling the gas from the resulting solution by heat, cooling theexpelled gas, and absorbing the relatively concentrated gas in anabsorbing medium other than said solution, whereby a solution ofrelatively high concentration is obtained, substantially as described.

5. The method of preparing solutions of gases, which consists indissolving a gas in a solvent by contact with the gas in diluted form,then ex elling the gas from the resulting solution by heat, cooling theex elled gas by transferring heat therefrom to t e inowing solution, andabsorbing the relatively concentrated gas in an absorbing medium otherthan said solution, whereby a solution of relatively high concentrationis substantially as described,

6. The method of preparing sulfite solutions, which consists indissolving sulfur dioxid in Water by contact with the gas in dilutedform, then expelling the gas by heat, cooling the expelled sulfur dioxidand absorbing the relatively concentrated gas in a sulfite solution,substantially as desiiribed.

7. The method of tions, which consists in dissolving; sulfur dioxid inwater by contact with the gas,in diluted form,-then expelling the gas'bvheat,

cooling the expelled gas by transferring heat obtained,

preparing suliite solutherefrom to the inflowing solution andabrelatively' concentrated gas in a sulfite solu 10 sorbing therelatively concentrated gas in a tion, substantially as described. I

sulfite solution, substantially as described. In.testimony whereof,I-afiix my sigmahSl. l'llhe method of preparingdsulfitg licl llllor,ture in presence of two Witnesses.

W '0 consists in bringing ilute s fur T v 7 dioxid into' resenoe ofWater and thereby HEB RY forming a's0 ution containing the gas; thenexpelling the gas from said solution, separat-- ing moisture therefrom,and absorbing the Witnesses: S. W. WILDER,

} ALICE B. PIPER.

